Renewable Renewable Energy:Energy:Energy:Energy:

Essential terms andEssential terms andEssential terms and Essential terms and concepts for citizens concepts for citizens

and advocatesand advocates

Courtesy of NASA

and advocatesand advocates

y

Contact InformationContact Information

P t Sh kP t Sh k

Contact InformationContact Information

Pete ShoemakerPete ShoemakerPacific Energy CenterPacific Energy CenterPacific Energy CenterPacific Energy Center

851 Howard St.851 Howard St.San Francisco, CA 94103San Francisco, CA 94103

(415) 973(415) 973 88508850(415) 973(415) 973--88508850pjsy@pge.compjsy@pge.compjsy@pge.compjsy@pge.com

The Big Picture

Courtesy of NASA

Courtesy of NASA

The sun is the only input.

Fossil fuels are millions of years of stored sun energy.

Which allows our lifestyle to expand to this.Which allows our lifestyle to expand to this.

Peak Oil

But the Age of Oil is temporary.But the Age of Oil is temporary.

Renewable Energy

And we’ll need a lot of different sources to replace it.

Conclusion

• Fossil fuels are an extremely dense, very portable form of concentrated energy.

• They are impossible to replace directly• They are impossible to replace directly.

• Key #1 to the transition to renewable energy is DIVERSITY.

Types of renewable energyyp gy

1. Hydroelectric1. Hydroelectric

2. Tidal

3. Geothermal

4 Bi4. Biomass

5. Wind5 d

6. Solar (electric, thermal)

Hydroelectric: large scaley gUses water flowing over a generator to spin a g pwheel and create electricity.V “ ”Very “green”.

Problems:

Courtesy of DOE/NREL

Ecological disruption, fish & wildlife

Tidal

Great potential, since t iwater carries

tremendous power.

Problems:Harsh conditions.Environmental disruptiondisruption.

Source: cbc.ca

Geothermal: large scalegUses the heat of the earth to create steam and turn a generatorand turn a generator.No emissions, produces 24/724/7.

Problems:

Courtesy of DOE/NREL

Site specific.Good sites are usually yaway from population.

Geothermal: small scale

Also called “Ground Source Heat Pump”

Uses the stable

Source Heat Pump .

Uses the stable temperature of the earth for heating and cooling

Problems:

Site location.

Expensive up-front.

BiomassSun energy

Stored in plants as they growas they grow

Still there when Can be extractedStill there when they’re harvested

Can be extracted and used

Biomass: BiodieselMade from cooking or other household oil.

Use it in cars just like gasoline.

Biomass: Ethanol (grass) or algae(g ) g

Doesn’t use food.

Much better than corn ethanol.Much better than corn ethanol.

Biomass: Methane

Turns cow dung into fuel.

Very cost-effective for appropriate sites.Keeps methane out of the air.

Wind• AbundantC b l• Can be low-cost

• Fast-growing

Courtesy of DOE/NREL

Problems:• Site-specific

y

• Large up-front cost• Environmental issues• Intermittent production

Windmills: Two different typesDefined by axis of blade rotation:

Horizontal axis(HAWT)

V ti l i( )

Vertical axis (VAWT)

Windmills: Swept area

Potential output is directly related to the input of wind energy: the amount of area “swept” by the windmillgy p y

HAWT: Larger is usually betterHorizontal axis: area = πR²

RR

Doubling the blade length increases the area 4x.

Power in the WindWind power is a VOLUME-based equation

xV = x³

x

xx

10 mph (10 x 10 x 10 = 1000)

5 h

10 mph ( )

( )

Doubling the wind speed increases the

5 mph (5 x 5 x 5 = 125)

Doubling the wind speed increases the potential wind power 8x.

Li htLi ht

Solar: Different TypesLight energyLight energyPhotovoltaic (PV)Electricity produced directly from lightElectricity produced directly from light

Heat energyHeat energyC t t d S l P (CSP)Concentrated Solar Power (CSP)Electricity produced by steam

Solar Water Heating (Solar Thermal)Heat produced in water, can be also used for space heating

All courtesy of DOE/NREL

Conclusion

• Fossil fuels are dirty but predictable in their output.

• Renewables are clean but multi-faceted• Renewables are clean but multi-faceted and variable.

• Key #2 to the transition to renewables is INTEGRATION.

Keys to Transition to Renewablesy

1. Diversity

2. Integration

Wind Array Variability

2007 CAISO (California Independent System Operator) report on Integration of Renewable Resources

PV Array Variability

Jay Apt and Aimee Curtright': "The Spectrum of Power from Utility-Scale Wind Farms and Solar Photovoltaic Arrays."

The Electric Grid

Electricity can be transported at the speed of light, therefore any point can be said to be connected to all others.

This network is called the GRID and is nation-wide.

Source: onearth.org Source: NREL

The Electric Grid

There are three main components of the grid:

Generation: Creating electricity.

Transmission: Moving it in bulk from t t di t ib ti tgenerators to distribution centers.

Distribution: Bringing it from centers (sub-stations) to individual homes and ( )businesses.

The Electric Grid

Source: PG&E

The Electric Grid

Above 50,000 V (69 kV up to 765 kV)

Step Sub-station

10,000 V (10 kV)

Transmissionp

up

10,000 V (10 kV)Step downDistribution

12 000 V (12 kV)120V – 240V

Generation12,000 V (12 kV)

Step down

Home480V

BusinessSource: NR

Grid Terms

Supply side Demand side

Generation Usage (load)

Grid Terms

Baseload: Minimum amount of power that is l d dalways needed

Seasonal load: Increase in demand in specific times of the year.

Peak load: Maximum amount neededPeak load: Maximum amount needed.

Capacity: Total power that the system can provide.

Grid Terms

BaseloadBaseloadBaseloadBaseload

PG&E 2006 Annual Usage

Grid Terms

Seasonal loadSeasonal load

PG&E 2006 Annual Usage

Grid Terms

Peak loadPeak loadPeak loadPeak load

PG&E 2006 Annual Usage

Highest demand occurs on only a few hours in the year

20000 Th t “50 H ”

14000

16000

18000

The top “50 Hours” represent 0.6% of the total hours in a year

10000

12000

14000

MW

s

4000

6000

8000

Load Duration CurveLoad Duration Curve

0

2000

1 501 1001 1501 2001 2501 3001 3501 4001 4501 5001 5501 6001 6501 7001 7501 8001 8501

Time

Load Duration CurveLoad Duration Curve

Grid Terms

CapacityCapacityCapacityCapacity

PG&E 2006 Annual Usage

Grid Terms

Unused CapacityUnused Capacity

PG&E 2006 Annual Usage

Grid Terms

Spread out the demand and you Spread out the demand and you p yp ycan lower the capacity need.can lower the capacity need.

PG&E 2006 Annual Usage

Grid Terms

Demand Management or

D d id M tDemand-side Management

Load-shifting

“How do you get people to use less power during peak times and morepower during peak times and more during off-peak?”

Demand Management Strategies

1. Reduce overall load.-- Energy efficiency, conservation

2. Inform people so they can cooperate voluntarily.

P bli it “Fl Y P ” l t-- Publicity, “Flex Your Power” alerts3. Create the ability to remotely turn off

t i licertain appliances.-- Smart AC, smart meters, etc.

4 Ch f k4. Charge more for peak usage.-- Time-of-Use rates, Peak-Time pricing

d th… and others.

Grid Integration Challenges

Source: onearth.org

Grid Integration Challenges1. How do you ensure a constant baseload?2 How can you handle daily variability?2. How can you handle daily variability?3. How can you predict output and budget

appropriately?appropriately?4. What storage devices are available and

practical?practical?-- The more storage, the more load shifting possible.

Grid Integration Challenges

1. How do you pay people for renewable energy?energy?

2. How MUCH do you pay people for renewable energy?renewable energy?

3. Should you pay differently for different types of renewables?types of renewables?

Methods of Payment

Two fundamentally different concepts:

Net MeteringServes the onsite load FIRST, then Se es t e o s te oad S , t einteracts with the utility grid.

One meter

Feed-in TariffDoes not serve the onsite load andDoes not serve the onsite load and ONLY interacts with the utility grid.

Two meters

Net Metering

MeterMeter

Customer side Utility side

Net Metering

Generation: 3 kWh Surplus: 2 kWh

MeterMeter

Load: 1 kWhCash credit: $ .602 kWh @ $(going rate)

Customer side Utility side

Net Metering

Generation: 1 kWh Surplus: 0 kWh

MeterMeter

Load: 1 kWhCash credit: $ .00

Customer side Utility side

Net Metering

Need: 1 kWhGeneration: 0 kWh

MeterMeter

Load: 1 kWhCash debit: $ .091 kWh @ $(going rate)

Customer side Utility side

Net Metering

kWh/mo

Average monthly usagePV system production

750 Roll over

500

250

OctoberMay April“SUMMER” “WINTER”

Net Metering

kWh/mo

Average monthly usagePV system production

750The surplus covers the shortfall, and your yearly bill is minimal.

500

250

OctoberMay April“SUMMER” “WINTER”

Net Metering

kWh/mo

Average monthly usagePV system production

750PV system produces less than your yearly usage.

500You pay this amount

250

OctoberMay April“SUMMER” “WINTER”

Net Metering

kWh/mo

Average monthly usagePV system production

750PV system produces more than your yearly usage.

500You are paid a different rate for this amount You are paid a different rate for this amount –– TBD.TBD.

250

OctoberMay April“SUMMER” “WINTER”

Net Metering

PV system production

MeterMeterInverter data

Customer side Utility side

Feed-in Tariff

Generation track

Feed-in (credit) ( )Meter

Usage (debit) Meter

Usage track

Net Metering

MeterMeter

Customer side Utility side

Comparison

Net Metering Feed-in Tariff

1. One meter2. One yearly payment

1. Two meters2 One monthly check2. One yearly payment

(check), net amount3. Often not easy to

d t i PV

2. One monthly check, one monthly bill

3. Easy to determine PV determine PV production

4 Payback can vary

yproduction

4. Payback usually much more predictable4. Payback can vary

depending on your tier usage

more predictable

Rate StructuresNet Metering: Tiered rate—the more you use, the more you pay.

PG&E E-1 Residential Rate 6/1/10

40.0 40.040 0

45.0

29.130.0

35.0

40.0

kWh

11.9 13.515.0

20.0

25.0

Cen

ts p

er

0.0

5.0

10.0

Less than 101% 131% 201% Over 300%Less than100%

101% -130%

131% -200%

201% -300%

Over 300%

Percentage of baseline allocation

Rate Structures

Feed-in Tariff: Fixed rate over time, possibly adjusting for inflation.

20-year Feed-in Tariff

20

25

r kW

h

5

10

15

nts

paid

per

0

5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Cen

Years

Rate Structures

Can have a mixture of bothIn PG&E territory:In PG&E territory:

• Systems from 1 kW to 1 mW (1,000 W to 1,000,000 W) are under Net Meteringare under Net Metering

• Systems above 1 mW are on Feed-in Tariffs

Feed-in Tariffs: How much to pay?

• Should it be higher than non-renewables?

• Should it be fixed or according to some kind of “profitability index”?p y

• Should you pay different amounts for different renewables?renewables?

“Grid Parity”When the price per kWh of electricity from a renewable source is equal to the current average grid price.

PV example:System net cost: $20,000, lifetime maintenance $4,000.

Expected to generate average of 5,000 kWh per year for 30 years, total of 150,000 kWh.

$24,000 / 150,000 = $ .16 per kWh

Current PG&E average price = $ .16 per kWhCu e t G& a e age p ce $ 6 pe

= Grid Parity

Renewable Energy Credits

• Called RECs or “green tags”• The “green attribute” of the power• The “green attribute” of the power• Connected to carbon offset accounting

Central feature of a system to move money from polluters to non pollutersfrom polluters to non-polluters.

Carbon Offsets

• Making activity “carbon neutral”Making activity carbon neutral• Funding projects that remove as

much carbon as you generatemuch carbon as you generate• Additional social & business image

lvalue

Keys to Transition to Renewablesy

1. Diversity

2. Integration

3. Economics

Environmental ImpactL PV i h d

M f t & M t i l

Large PV array in the desert.

T i i

Manufacture & Materials

Construction

Transmission

Generation &

Construction

Maintenance

Keys to Transition to Renewablesy

1. Diversity

2. Integration

3. Economics

4 Environmental impact4. Environmental impact

Keys to Transition to Renewablesy

1. Diversity-- Need a wide variety, fit technology to site

2. Integration2. Integration-- Ensure baseload, reduce variability

3 Economics3. Economics-- Good incentives, fair to all ratepayers

4. Environmental impact-- All aspects of project

Smart Grid

Source: EPRI Intelligrid Architecture

Source: NPR http://www.npr.org/templates/story/story.php?storyId=110997398

Courtesy of NASA